Steiff Teddy Bears-what is a Growler?

I am getting a steiff Teddy my very first one for my 18th Birthday (well you have to start somewhere lol) and i have been looking them up on the internet and i know what mohair is but i don't know what the growler is i have a faint idea that it is something to do with the bear growling lol but apart from that i don't know how it works or if it effects the value of the bear if anyone knows could you please let me know.

Thank You

Also is the growler worth having, i mean is it any good sound wise?

I ha a dream that a man told me you turn the bear upside down and when you put it the right way up again it causes air to get trapped in a tube and causes the growling effect lol please save my sanity from these crazy dreams.